Brighton-Best Hex Head Lag Screws - Also known as Lag Bolts, Lag Screws come in longer lengths than wood screws and are easy to tighten with a wrench. Hex head fasteners can be driven with simple wrenches, and require minimal clearance above the fastener because they can be driven or loosened from the side. Length is measured from under the head. Fasteners are typically made of low-carbon steel. Porteous (PFC) 00110-2872-024.